well dex will gunk up when it is mixed with regular antifreeze, so if you do do a conversion, make sure u get all of the old dex out! or you will be taking ur radiator to a shop to be cleaned out or your block, and possible heater core.

 

Okay so how does everyone flush their radiator system to rid it of the new DEX antifreeze? I personally have used the red stuff when it first came it as I recall and it ate a hole in my heater core of my 1990 Model Chevy Silverado with a 5.7. My mechanic buddy said to replace the heater core (obviously) and get that, "G@% DAM DEX **** out of that truck! It is the worse stuff you can use. It is acidic and I have replaced heater cores, radiators and waterpumps ever since GM has been using that stuff." So needless to say I replaced it with Green Antifreeze. I drained it added pure water too it. Ran it, drained it... over and over, overa 2 day period. Think I got it all out? I feel like I did and I never went back to the DEX and never had a problem again. So I will be doing the same to my 2004 GMC Sierra too at 100,000 miles.Is there a problem with replacing the DEX with regular old green antifreeze in my 04?

 

nope best thing you can do get that "G@#$% Damn dex out" never liked it any way. and really only 2 good fills with water will do the job

 

I guess I just like to be thorough... lol I am not to far from 100,000 miles anyhow. Then it will be out with the red and in with the Green.

 

I'd get it out as soon as you can. I have no idea where gm came up with this ****. The dex cool is horrible wait to you see what it does to your hands if you get the dex cool on it. My hands started to burn and developed a rash. If it is that acidic on your hands just think what it is doing to the gaskets in your truck.

 

Hey Adam, you should taste it j/k.........

Thanks for all the responses - I didn't have the time to do full flush, and since it had Dex already I just added to it. I'll have it flushed and refilled with something else here soon. I don't have anywhere to drain all the chemicals and don't want to just let it run down the gutter.

On plus side, took the truck in for transmission fluid change/flush and new filter, and had 'em give the whole thing a thorough inspection in case there's anything else I should be paying attention to and she got a clean bill of health I know anything can happen but I'm relieved there's nothing on the verge of catastrophic failure.

 

I understand everybodys' hatred of Dex-cool but, the Prestone Dex-cool is NOT the GM Dex-cool. Prestone just puts an additive that turns the stuff orange/pink. The OEM GM Dex-cool is the bad stuff that destroys intake gaskets, water pumps ETC. ETC. If you just drain all of the GM Dex-cool out and replace it with Prestone 50/50 pre-mixed Dex-cool, you will have no problems at all. It is not necessary to go through all of the flushing and draining with water. I have 210,500 miles on my Tahoe and I have Prestone Dex-cool in for the last 110,500 miles and I have had no coolant related problems.

 

Your truck with the 305 (5.0 liter) is famous for intake gasket problems. You won't see any problems untill it is to late. You are probably looking at a $500 bill from a shop to do the intake gaskets. Even if you pay for a flush and fill your only looking at $100. I can do my own flush for about $30.

 

The intake gasket problem is not limited to the 305s. It effects all of the v-6 and v-8 engines with OEM GM Dex-cool. There was a class action lawsuit that was won by the class, however the class was limited to the v-6snot the v-8s. Anyway adampgasser, you are correct that these engines are famous for lower intake gasket leaks. If the intake gaskets associated to this forum are not leaking, it is only a matter of time before they do. All of the flushing going on will bring on a lower intake gasket leak. You will be lucky if it leaks outside of the engine. If this gaskey fails internally it will cause severe damage if not caught in time..CONSIDER YOURSELF WARNED...When you DO replace these lower intake gaskets make sure you do not over-tighten the intake bolts. This also is the cause of many repeat intake gasket failures.....Good luck

 

Ah so I'm learning a thing or 2 on this board... I just figged Prestone Dex = GM Dex... I used Prestone, not GM. I've only had this truck a few months so I have NO idea what was in the system before but it was SOME kind of orangey-red coolant. I've determined it's got an aftermarket radiator - no idea when that was installed - and hope GM Dex wasn't used. So far, intake manifold gasket is intact - mechanic just checked that out for me. Probably oughta get flushed anyway... next paycheck